Solar Savings Calculator
Estimate a rooftop solar system size, cost, and payback period from your average monthly electricity units.
What this estimate assumes
- Installed cost
- Rs 140,000 per kW
- Average generation
- 4.5 units / kW / day
- Net-metering buyback
- Rs 11 per unit
These figures reflect publicly reported pricing for on-grid residential systems without battery storage. Real costs vary by installer, panel and inverter brand, and city, so treat the output as a planning estimate rather than a quote.
Savings are calculated against your current blended rate per unit — that is, what you actually pay per unit once slab position, FPA, GST and fixed charges are taken into account. That matters because the higher your consumption, the higher the slab you are displacing, and the more each solar unit is worth to you.
Net metering was repealed in February 2026
NEPRA's Prosumer Regulations, 2026 replaced net metering with net billing: exported units are now credited at the national average energy purchase price rather than exchanged one-for-one against imports. This estimate values exports at roughly Rs 11 per unit, but the substantive point is that the value of rooftop solar now sits in consuming your own generation rather than selling it back.
Sizing, and why the first kilowatt is the best one
This calculator sizes a system to roughly match your monthly consumption, then values the units it displaces at your own blended rate — what you actually pay per unit once slab position, adjustments and taxes are counted. That blended rate is the number that matters, and it rises with consumption, which is why the same system saves a heavy user far more than a light one.
| Monthly units | System (kW) | Cost (Rs) | Blended rate (Rs/unit) | Payback (years) |
|---|---|---|---|---|
| 200 | 1.5 | 210,000 | 14.5 | 6.1 |
| 600 | 4.5 | 630,000 | 39.2 | 2.2 |
A protected household at 200 units buys electricity cheaply, so displacing it is worth less and payback is slower. The arithmetic favours households already deep into the unprotected slabs.
The corollary is that oversizing has become expensive. Under the rules in force since February 2026, generation beyond what you consume as it is produced is credited at a wholesale price rather than exchanged against your imports, so the last panel on the roof pays back far more slowly than the first. Size to daytime load, not to annual units.
What this estimate does not capture
The most important limitation is timing. The calculator assumes the units you generate displace units you would otherwise have bought, which is true only to the extent that you consume them while the sun is up. A household whose load is mostly evening — lights, television, air conditioning after dark — will self-consume less than this assumes, and under net billing the difference is no longer made whole by exporting.
- Panel degradation, typically a fraction of a percent of output a year, which lengthens payback slightly over a system's life.
- Inverter replacement, usually needed once within the life of the panels and a real cost that is not in the installed price.
- Cleaning and maintenance, which matters more in dusty cities than most quotations admit.
- Battery storage, which changes the arithmetic substantially and is not modelled here.
- Financing. A system bought on instalments costs more than one bought outright, and the payback figure assumes the latter.
Sanctioned load is a hard ceiling
Your system may not exceed the sanctioned load recorded against your connection. If the size you want is above it, applying to enhance the sanctioned load is a separate process and is worth starting before you order equipment.
Questions
Is solar still worth it after the 2026 rule change?
For households with substantial daytime consumption, yes — the units you use as you generate them displace electricity at the retail tariff, which is several times what an exported unit now earns. For a household that is empty all day and heavy in the evening, the case is much weaker without storage.
What size system should I buy?
Size to the load you can actually consume during daylight rather than to your annual units. Under net billing, capacity beyond that earns a wholesale credit, so the marginal panel pays back far more slowly than the first one.
How accurate is the payback figure?
It is a planning estimate. It assumes an outright purchase, full self-consumption of what is generated, no inverter replacement and no degradation. Each of those pushes real payback out somewhat, so treat the figure as the optimistic end of a range.
Do I need approval before installing?
For a grid-connected system, yes. The system must not exceed your sanctioned load, and it goes through an application, agreement and NEPRA concurrence before the billing arrangement starts. An off-grid system with no connection to the network does not.
Will solar make me a protected consumer again?
It can. Protected status is assessed on units billed each month, so a system that pulls you below 200 units moves you to the cheaper table — which also means each displaced unit is then worth less, since you are buying more cheaply.